THERE aren’t many bands as devoted to the fans as Queensryche. The pre-grunge Seattle rockers, who’ve shoveled against the shifting sands of style like a chain gang for the last 20 years, played two concerts in one Thursday night at the Beacon.

Fronted by singer Geoff Tate, the band kicked off its three-hour show with a career-spanning retrospective, laying out its distinctive metal, guitar-powered sound with layered, almost orchestral arrangements that recall Queen and even Pink Floyd.

There were frantic headbanging rockers like “Jet City Woman,” but Tate and the boys sounded their best on anthems and power ballads like “I Don’t Believe in Love” and the show-stopping “Silent Lucidity.”

But the second act was the real reason the Queensryche cult had gathered.

For the first time in more than 15 years, the band played its rock opera, “Operation: Mindcrime,” in its entirety.

The loose story, set to crashing metal, centers on a drug addict who falls in love with a hooker-turned-nun. Together, they uncover an authoritarian plot to quash freedom and rub out individuality.

The fans hugged and high-fived each other at each twist in the song cycle.